81638200 has 48 divisors (see below), whose sum is σ = 216928080. Its totient is φ = 27989760.

The previous prime is 81638197. The next prime is 81638203. The reversal of 81638200 is 283618.

It is an interprime number because it is at equal distance from previous prime (81638197) and next prime (81638203).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81638203) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27757 + ... + 30556.

It is an arithmetic number, because the mean of its divisors is an integer number (4519335).

Almost surely, 2^81638200 is an apocalyptic number.

It is an amenable number.

81638200 is an abundant number, since it is smaller than the sum of its proper divisors (135289880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81638200 is a wasteful number, since it uses less digits than its factorization.

81638200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58336 (or 58327 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 81638200 is about 9035.3859906481. The cubic root of 81638200 is about 433.8082498654.

The spelling of 81638200 in words is "eighty-one million, six hundred thirty-eight thousand, two hundred".